1. Technical Field
This invention relates to the field of combinatorial chemistry. More specifically, the invention relates to a three-dimensional (3D) array of supports for solid-phase parallel synthesis and its method of use.
2. Background Art
In recent years the field of combinatorial chemistry has become increasingly important due to the rapidly growing number of potential drug targets emerging from molecular biology research. In past decades, the synthesis of organic chemicals in the pharmaceutical industry was slow and costly. Combinatorial chemistry offers a set of techniques for creating a multiplicity of compounds that may then be screened for bioactivity.
In one use of combinatorial chemistry, large libraries of molecules are produced in parallel while attached to solid-phase supports. A 96-well plate is common tool used in solid-phase parallel synthesis of molecules. Essentially, the 96-well plate is an array of wells having eight rows of twelve wells, wherein each well may be identified by its unique location in the array. A predetermined amount of a solid support material, often resin beads about 20 μm to 500 μm in diameter, is placed in each well. The solid support is functionalized prior to placement in the wells such that an initial building block of the molecule to be synthesized on the support will bond with the support. Typical resin beads are manufactured by copolymerizing styrene and divinylbenzene monomers, although other monomers may be used, to produce the beads. As taught in the art, other solid supports may be used, including controlled pore glass, polyacrylamides, poly(ethylene glycol), poly(ethylene glycol)-monomethyl ether, silica gel, cellulose, acrylic acid grafted polypropylene, acid grafted polyethylene, and still other materials. Various functionalities may be chemically joined, typically by covalent bonding, to the resins, such as carboxylic acid, alcohol, halomethyl, chloromethyl (Merrifield), amino, and aminomethyl functionalities. Initial building blocks are then chemically joined to the functionalities and additional building blocks are added sequentially, synthesizing molecules one building block at a time on the support. The addition of building blocks may be designed such that a different series of building blocks is added to each well in the 96-well plate. Thus, the series of reactions that build the molecules on the solid support will yield a different molecule in each well. Accordingly, for a 96-well plate, 96 unique molecules may be synthesized in parallel.
Once synthesized, the molecules may be cleaved from the solid support or left attached, screened for bioactivity, stored in a library of molecules, etc. Many apparatus and methods have been developed for increasing the rapidity with which molecules may be synthesized, cleaved, screened and stored. Examples of some of the apparatus and methods are described in the following patents: Zambias et al., U.S. Pat. No. 5,712,171; Hudson et al., U.S. Pat. Nos. 5,591,646 and 5,585,275; Baker et al., U.S. Pat. No. 5,716,584; DeWitt et al., U.S. Pat. No. 5,714,127; Winkler et al., U.S. Pat. No. 5,677,195; Lam et al., U.S. Pat. No. 5,651,943; Zanzucchi et al., U.S. Pat. No. 5,643,738; Sundberg et al., U.S. Pat. No. 5,624,711; Cargill et al., U.S. Pat. No. 5,609,826; Lee et al., U.S. Pat. No. 5,571,869; Brennan, U.S. Pat. No. 5,529,756; Nokihara et al., U.S. Pat. No. 5,395,594; Goldberg et al., U.S. Pat. No. 5,376,400; Berg et al., U.S. Pat. No. 5,258,454; Cahalan et al., U.S. Pat. No. 5,229,172; Frank et al., U.S. Pat. No. 4,689,405; Hamill, U.S. Pat. No. 4,728,502; and Houghten, U.S. Pat. No. 4,631,211, each of which is herein incorporated by reference for its pertinent and supportive teachings.
In each of the above patents, the number of molecules that may be synthesized is typically limited by the number of available wells. It is possible to place a mixture of supports having different initial building blocks in one well and thus synthesize multiple molecules in one well. However, it is difficult and costly using current technology to later segregate the molecules when needed. Accordingly, plates have been fabricated having more rows and columns of wells than the typical 96-well plate. For example, a 384-well plate is also common. Generally, the number of wells is increased by decreasing the size of individual wells such that more wells will fit within the size limitations of a well plate. However, if the wells are smaller, then less support material may be placed in a given well and, in turn, a lesser amount of a molecule may be synthesized in the well.
Often, portions of the synthesis process are conducted with automated devices that distribute among the wells the correct amount and type of reagents needed to add building blocks. One size limitation of a well plate is the maximum dimension that an existing automated device will accept. Other size limitations may exist depending upon other equipment used in the synthesis process that has been fabricated to accommodate a particular size of well plate. Also, the size of individual wells may be limited by equipment constraints. It is conceivable that an individual well could become too small to be compatible with the devices used to distribute reagents, insert and retrieve solid supports, etc. Wells that are too small could introduce errors into the synthesis process if reagents and supports cannot be accurately delivered to and retrieved from the wells. In addition, the automated devices and other equipment are often quite costly and changing to a new well plate, even though improved, may require the replacement of equipment designed to accommodate the new well plate. Therefore, there existed a need to increase the number of molecules that may be accurately synthesized in a well plate without the expense of replacing automated devices or other equipment.
After synthesis, molecules are screened and then stored, since a need may arise to conduct further screening or testing of a given batch of molecules. The stored molecules are referred to as a library of molecules. A library can take many forms, but often comprises a collection of small vials, capped well plates, or similar storage containers, each vial or well containing a solution with a single type of molecule that was synthesized in a well plate and, often, cleaved from a solid support. The collection of vials, well plates, etc. can be difficult to manage, since combinatorial chemistry technology is capable of yielding an immense number of unique molecules. That capability translates into an equally immense number of vials, wells, etc. Accordingly, there also existed a need to improve the method of forming libraries and provide less awkward management thereof.
Thus, it can be seen from the above discussion that it would be an improvement in the art to provide a technology and tools that increase the number of molecules that may be accurately synthesized using existing and new equipment and to provide an improved method of creating a library of the molecules synthesized.